114 lines
3.7 KiB
TypeScript
114 lines
3.7 KiB
TypeScript
import type {BuiltIns} from './internal';
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/**
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@see PartialDeep
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*/
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export interface PartialDeepOptions {
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/**
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Whether to affect the individual elements of arrays and tuples.
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@default true
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*/
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readonly recurseIntoArrays?: boolean;
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}
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/**
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Create a type from another type with all keys and nested keys set to optional.
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Use-cases:
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- Merging a default settings/config object with another object, the second object would be a deep partial of the default object.
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- Mocking and testing complex entities, where populating an entire object with its keys would be redundant in terms of the mock or test.
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@example
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```
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import type {PartialDeep} from 'type-fest';
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const settings: Settings = {
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textEditor: {
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fontSize: 14;
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fontColor: '#000000';
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fontWeight: 400;
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}
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autocomplete: false;
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autosave: true;
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};
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const applySavedSettings = (savedSettings: PartialDeep<Settings>) => {
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return {...settings, ...savedSettings};
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}
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settings = applySavedSettings({textEditor: {fontWeight: 500}});
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```
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By default, this also affects array and tuple types:
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```
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import type {PartialDeep} from 'type-fest';
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interface Settings {
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languages: string[];
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}
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const partialSettings: PartialDeep<Settings> = {
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languages: [undefined]
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};
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```
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If this is undesirable, you can pass `{recurseIntoArrays: false}` as the second type argument.
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@category Object
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@category Array
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@category Set
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@category Map
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*/
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export type PartialDeep<T, Options extends PartialDeepOptions = {}> = T extends BuiltIns
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? T
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: T extends Map<infer KeyType, infer ValueType>
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? PartialMapDeep<KeyType, ValueType, Options>
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: T extends Set<infer ItemType>
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? PartialSetDeep<ItemType, Options>
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: T extends ReadonlyMap<infer KeyType, infer ValueType>
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? PartialReadonlyMapDeep<KeyType, ValueType, Options>
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: T extends ReadonlySet<infer ItemType>
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? PartialReadonlySetDeep<ItemType, Options>
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: T extends ((...arguments: any[]) => unknown)
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? T | undefined
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: T extends object
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? T extends ReadonlyArray<infer ItemType> // Test for arrays/tuples, per https://github.com/microsoft/TypeScript/issues/35156
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? Options['recurseIntoArrays'] extends false // If they opt out of array testing, just use the original type
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? T
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: ItemType[] extends T // Test for arrays (non-tuples) specifically
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? readonly ItemType[] extends T // Differentiate readonly and mutable arrays
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? ReadonlyArray<PartialDeep<ItemType | undefined, Options>>
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: Array<PartialDeep<ItemType | undefined, Options>>
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: PartialObjectDeep<T, Options> // Tuples behave properly
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: PartialObjectDeep<T, Options>
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: unknown;
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/**
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Same as `PartialDeep`, but accepts only `Map`s and as inputs. Internal helper for `PartialDeep`.
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*/
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interface PartialMapDeep<KeyType, ValueType, Options extends PartialDeepOptions> extends Map<PartialDeep<KeyType, Options>, PartialDeep<ValueType, Options>> {}
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/**
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Same as `PartialDeep`, but accepts only `Set`s as inputs. Internal helper for `PartialDeep`.
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*/
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interface PartialSetDeep<T, Options extends PartialDeepOptions> extends Set<PartialDeep<T, Options>> {}
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/**
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Same as `PartialDeep`, but accepts only `ReadonlyMap`s as inputs. Internal helper for `PartialDeep`.
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*/
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interface PartialReadonlyMapDeep<KeyType, ValueType, Options extends PartialDeepOptions> extends ReadonlyMap<PartialDeep<KeyType, Options>, PartialDeep<ValueType, Options>> {}
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/**
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Same as `PartialDeep`, but accepts only `ReadonlySet`s as inputs. Internal helper for `PartialDeep`.
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*/
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interface PartialReadonlySetDeep<T, Options extends PartialDeepOptions> extends ReadonlySet<PartialDeep<T, Options>> {}
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/**
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Same as `PartialDeep`, but accepts only `object`s as inputs. Internal helper for `PartialDeep`.
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*/
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type PartialObjectDeep<ObjectType extends object, Options extends PartialDeepOptions> = {
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[KeyType in keyof ObjectType]?: PartialDeep<ObjectType[KeyType], Options>
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};
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